Paid for shoe i have yet to receive

I ordered a shoe and a wrong one was delivered, i requested a return and the shoe was collected on the 23rd of January. At first customer services disputed it was a wrong shoe and requested the picture of what I ordered which i provided,after back and forth Chantal from customer services admitted fault and said it was their error, they will exchange. It has been 2 weeks of silence from their side no exchange or credit and they are ignoring my emails. I am frusturated to the core